As a conventional digital printing press, there exists an inkjet type described in, for example, patent literature 1. In the digital printing press disclosed in patent literature 1, a sheet rotates together with a printing cylinder and is thus transported between an inkjet nozzle head (to be simply referred to as an inkjet head hereinafter) and the printing cylinder.
Printing is performed by ejecting ink from the inkjet head to the sheet in a state in which the sheet is located between the printing cylinder and the inkjet head. To obtain high print quality, the inkjet head is arranged at a position where a small gap is formed with respect to the sheet. For this reason, if the sheet partially floats up from the printing cylinder, the distance between the sheet and the inkjet head changes to cause a print error. Additionally, the floating portion may contact the inkjet head, and the inkjet head may be damaged.
To prevent such an error, the conventional digital printing press includes a floating detector configured to detect a portion of a sheet floating from the printing cylinder.
The conventional digital printing press including an abnormality detector like the floating detector employs an arrangement that stops a motor for driving the printing cylinder and stops the printing cylinder upon detecting an abnormality during printing.